CPM154 for me. I hate working with S30V, so I am biased. There are a number of makers that don't care for S30V...it's not just me. There have been problems noted with inconsistent heat treats from batch to batch....among other things.
The difference in 154CM and CPM154 is the process of making the steel...the "recipe" is the same. CPM stands for Crucible Particle Metallurgy. Here is what Crucible says about the process:
Although the steel is very homogeneous in the molten state, as it slowly solidifies in the molds, the alloying elements segregate resulting in a non-uniform as-cast microstructure.
The CPM process also begins with a homogeneous molten bath similar to conventional melting. Instead of being teemed into ingot molds, the molten metal is poured through a small nozzle where high pressure gas bursts the liquid stream into a spray of tiny spherical droplets. These rapidly solidify and collect as powder particles in the bottom of the atomization tower. The powder is relatively spherical in shape and uniform in composition as each particle is essentially a micro-ingot which has solidified so rapidly that segregation has been suppressed. The carbides which precipitate during solidification are extremely fine due to the rapid cooling and the small size of the powder particles. The fine carbide size of CPM steel endures throughout mill processing and remains fine in the finished bar.
CPM154, even though it is the same makup as 154CM, will produce a superior blade because of the process explained above. Carbides in blade steel are the measuring stick, so to speak, with blade steels, and fine carbides, more evenly distributed in the blade, is what you want...that's the ideal. That's what you get with the CPM process.
Here is what the CPM blade steel looks like under an electron microscope for comparison, notice the smaller carbides and more even distribution:
I have a post in this same Knives forum that shows why I love CPM-154. Check it out:
https://www.24hourcampfire.com/ubbt...54-blade-steel-in-my-knives#Post13207293